Compiling sage on external memory

Hello
I would like to build sage on external hard disk, my primary machine is running on ubuntu 12.04. I have cloned a certain branch and tried to run make but it says permission denied. I have tried changing the permissions by giving in chmod -R 775 but that does not seem to change anything.

Comments

I have tried this but the permissions seem not to change ...
rwx------ is what the sage folder has on the external hard disk.
When I give in chmod -R 755 <path to="" sage=""> and do an ls -l there is no change in the permission set.
Any help on this would be great ... Thanks :)